/*
 * Copyright (c) 1999, 2001, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.naming.directory;

/**
 * This class represents a modification item.
 * It consists of a modification code and an attribute on which to operate.
 * <p>
 * A ModificationItem instance is not synchronized against concurrent
 * multithreaded access. Multiple threads trying to access and modify
 * a single ModificationItem instance should lock the object.
 *
 * @author Rosanna Lee
 * @author Scott Seligman
 * @since 1.3
 */

/*
  *<p>
  * The serialized form of a ModificationItem object consists of the
  * modification op (and int) and the corresponding Attribute.
*/

public class ModificationItem implements java.io.Serializable {

  /**
   * Contains an integer identify the modification
   * to be performed.
   *
   * @serial
   */
  private int mod_op;
  /**
   * Contains the attribute identifying
   * the attribute and/or its value to be applied for the modification.
   *
   * @serial
   */
  private Attribute attr;

  /**
   * Creates a new instance of ModificationItem.
   *
   * @param mod_op Modification to apply.  It must be one of: DirContext.ADD_ATTRIBUTE
   * DirContext.REPLACE_ATTRIBUTE DirContext.REMOVE_ATTRIBUTE
   * @param attr The non-null attribute to use for modification.
   * @throws IllegalArgumentException If attr is null, or if mod_op is not one of the ones specified
   * above.
   */
  public ModificationItem(int mod_op, Attribute attr) {
    switch (mod_op) {
      case DirContext.ADD_ATTRIBUTE:
      case DirContext.REPLACE_ATTRIBUTE:
      case DirContext.REMOVE_ATTRIBUTE:
        if (attr == null) {
          throw new IllegalArgumentException("Must specify non-null attribute for modification");
        }

        this.mod_op = mod_op;
        this.attr = attr;
        break;

      default:
        throw new IllegalArgumentException("Invalid modification code " + mod_op);
    }
  }

  /**
   * Retrieves the modification code of this modification item.
   *
   * @return The modification code.  It is one of: DirContext.ADD_ATTRIBUTE
   * DirContext.REPLACE_ATTRIBUTE DirContext.REMOVE_ATTRIBUTE
   */
  public int getModificationOp() {
    return mod_op;
  }

  /**
   * Retrieves the attribute associated with this modification item.
   *
   * @return The non-null attribute to use for the modification.
   */
  public Attribute getAttribute() {
    return attr;
  }

  /**
   * Generates the string representation of this modification item,
   * which consists of the modification operation and its related attribute.
   * The string representation is meant for debugging and not to be
   * interpreted programmatically.
   *
   * @return The non-null string representation of this modification item.
   */
  public String toString() {
    switch (mod_op) {
      case DirContext.ADD_ATTRIBUTE:
        return ("Add attribute: " + attr.toString());

      case DirContext.REPLACE_ATTRIBUTE:
        return ("Replace attribute: " + attr.toString());

      case DirContext.REMOVE_ATTRIBUTE:
        return ("Remove attribute: " + attr.toString());
    }
    return "";      // should never happen
  }

  /**
   * Use serialVersionUID from JNDI 1.1.1 for interoperability
   */
  private static final long serialVersionUID = 7573258562534746850L;
}
